Computer Vision Syndrome describes a group of eye and vision-related problems that result from prolonged computer use. Many individuals experience eye discomfort and vision problems when viewing a computer screen for extended periods. The level of discomfort appears to increase with the amount of computer use.
The most common symptoms associated with Computer Vision Syndrome (CVS) are:
- blurred vision
- dry eyes
- neck and shoulder pain
These symptoms may be caused by:
- poor lighting
- glare on the computer screen
- improper viewing distances
- poor seating posture
- uncorrected vision problems
- a combination of these factors
The extent to which individuals experience visual symptoms, depends on the level of their visual abilities and the amount of time spent looking at the computer screen. Uncorrected vision problems like farsightedness and astigmatism, inadequate eye focusing or eye coordination abilities, and aging changes of the eyes, such as presbyopia, can all contribute to the development of visual symptoms when using a computer.
Many of the visual symptoms experienced by computer users are only temporary and will decline after stopping computer work. However, some individuals may experience continued reduced visual abilities, such as blurred distance vision, even after stopping work at a computer. If nothing is done to address the cause of the problem, the symptoms will continue to recur and perhaps worsen with future computer use.
Prevention or reduction of the vision problems associated with Computer Vision Syndrome involves taking steps to control lighting and glare on the computer screen, establishing proper working distances and posture for computer viewing, and assuring that even minor vision problems are properly corrected.
How is Computer Vision Syndrome diagnosed?
Computer Vision Syndrome can be diagnosed through a comprehensive eye examination. Testing, with special emphasis on visual requirements at the computer working distance, may include:
- Patient history to determine any symptoms the patient is experiencing and the presence of any general health problems, medications taken, or environmental factors that may be contributing to the symptoms related to computer use.
- Visual acuity measurements to assess the extent to which vision may be affected.
- A refraction to determine the appropriate lens power needed to compensate for any refractive errors (nearsightedness, farsightedness or astigmatism).
- Testing how the eyes focus, move and work together.
In order to obtain a clear, single image of what is being viewed, the eyes must effectively change focus, move and work in unison. This testing will look for problems that keep your eyes from focusing effectively or make it difficult to use both eyes together.
This testing may be done without the use of eye drops to determine how the eyes respond under normal seeing conditions. In some cases, such as when some of the eyes' focusing power may be hidden, eye drops may be used. They temporarily keep the eyes from changing focus while testing is done.
Using the information obtained from these tests, along with results of other tests, your optometrist can determine if you have Computer Vision Syndrome and advise you on treatment options.How is Computer Vision Syndrome treated?
Solutions to computer-related vision problems are varied. However, CVS can usually be alleviated by obtaining regular eye care and making changes in how you view the computer screen.Eye Care
In some cases, individuals who do not require the use of eyeglasses for other daily activities may benefit from glasses prescribed specifically for computer use. In addition, persons already wearing glasses may find their current prescription does not provide optimal vision for viewing a computer.
Eyeglasses or contact lenses prescribed for general use may not be adequate for computer work. Lenses prescribed to meet the unique visual demands of computer viewing may be needed. Special lens designs, lens powers or lens tints or coatings may help to maximize visual abilities and comfort.
Some computer users experience problems with eye focusing or eye coordination that can't be adequately corrected with eyeglasses or contact lenses. A program of vision therapy may be needed to treat these specific problems. Vision therapy, also called visual training, is a structured program of visual activities prescribed to improve visual abilities. It trains the eyes and brain to work together more effectively. These eye exercises help remediate deficiencies in eye movement, eye focusing and eye teaming and reinforce the eye-brain connection. Treatment may include office-based as well as home training procedures.Viewing the Computer
Positioning of the computer - Some important factors in preventing or reducing the symptoms of CVS have to do with the computer and how it is used. This includes lighting conditions, chair comfort, location of reference materials, position of the monitor, and the use of rest breaks.
Location of computer screen - Most people find it more comfortable to view a computer when the eyes are looking downward. Optimally, the computer screen should be 15 to 20 degrees below eye level (about 4 or 5 inches) as measured from the center of the screen and 20 to 28 inches from the eyes.
Reference materials - These materials should be located above the keyboard and below the monitor. If this is not possible, a document holder can be used beside the monitor. The goal is to position the documents so you do not need to move your head to look from the document to the screen.
Lighting - Position the computer screen to avoid glare, particularly from overhead lighting or windows. Use blinds or drapes on windows and replace the light bulbs in desk lamps with bulbs of lower wattage.
Anti-glare screens - If there is no way to minimize glare from light sources, consider using a screen glare filter. These filters decrease the amount of light reflected from the screen.
Seating position - Chairs should be comfortably padded and conform to the body. Chair height should be adjusted so your feet rest flat on the floor. If your chair has arms, they should be adjusted to provide arm support while you are typing. Your wrists shouldn't rest on the keyboard when typing.
Rest breaks - To prevent eyestrain, try to rest your eyes when using the computer for long periods. Rest your eyes for 15 minutes after two hours of continuous computer use. Also, for every 20 minutes of computer viewing, look into the distance for 20 seconds to allow your eyes a chance to refocus. To minimize your chances of developing dry eye when using a computer, make an effort to blink frequently. Blinking keeps the front surface of your eye moist.
Color vision deficiency is the inability to distinguish certain shades of color or in more severe cases, see colors at all. The term "color blindness" is also used to describe this visual condition, but very few people are completely color blind.
Most people with color vision deficiency can see colors, but they have difficulty differentiating between particular shades of reds and greens (most common) or blues and yellows (less common). People who are totally color blind, a condition called achromatopsia, can only see things as black and white or in shades of gray.
The severity of color vision deficiency can range from mild to severe depending on the cause. It will affect both eyes if it is inherited and usually just one if the cause for the deficiency is injury or illness.
Color vision is possible due to photoreceptors in the retina of the eye known as cones. These cones have light sensitive pigments that enable us to recognize color. Found in the macula, the central portion of the retina, each cone is sensitive to either red, green, or blue light, which the cones recognize based upon light wavelengths.
Normally, the pigments inside the cones register differing colors and send that information through the optic nerve to the brain enabling you to distinguish countless shades of color. But if the cones lack one or more light sensitive pigments, you will be unable to see one or more of the three primary colors thereby causing a deficiency in your color perception.
The most common form of color deficiency is red-green. This does not mean that people with this deficiency cannot see these colors at all; they simply have a harder time differentiating between them. The difficulty they have in correctly identifying them depends on how dark or light the colors are.
Another form of color deficiency is blue-yellow. This is a more rare and severe form of color vision loss, since persons with blue-yellow deficiency frequently have red-green blindness too. In both cases, it is common for people with color vision deficiency to see neutral or gray areas where a particular color should appear.What causes color vision deficiency?
Color deficiency is usually an inherited condition, but disease and injury can also result in color recognition loss.
Usually, color deficiency is an inherited condition caused by a common X-linked recessive gene, which is passed from a mother to her son. But disease or injury damaging the optic nerve or retina can also result in loss of color recognition. Some specific diseases that can cause color deficits are:
- macular degeneration
- Alzheimer's disease
- Parkinson's disease
- multiple sclerosis
- chronic alcoholism
- sickle cell anemia
Other causes for color vision deficiency include:
- Medications - certain medications such as drugs used to treat heart problems, high blood pressure, infections, nervous disorders and psychological problems can affect color vision.
- Aging - the ability to see colors can gradually lessen with age.
- Chemical Exposure - contact with certain chemicals such as fertilizers and styrene have been known to cause loss of color vision.
In the majority of cases, genetics is the predominate cause for color deficiency. About 8% of caucasian males are born with some degree of color deficiency. Women are typically just carriers of the color deficient gene, though approximately 0.5% of women have color vision deficiency. When the deficiency is hereditary, the severity generally remains constant throughout life. Inherited color vision deficiency does not lead to additional vision loss or blindness.How is color vision deficiency diagnosed?
Color deficiency can be diagnosed through a comprehensive eye examination. Testing will include the use of a series of specially designed pictures composed of colored dots, called pseudisochromatic plates, which include hidden numbers or embedded figures that can only be correctly seen by persons with normal color vision.
Pseudoisoschromatic plate testing can be used to determine if a color vision deficiency exists and the type of deficiency. However, additional testing may be needed to determine the exact nature and degree of color deficiency.
It is possible for a person to have poor color vision and not know it. Quite often, people with red-green deficiency aren't even aware of their problem since they've learned to see the "right" color. For example, tree leaves are green, so they call the color they see green.
Also parents may not suspect the condition in their children until a situation causes confusion or misunderstanding. Early detection of color deficiency is vital since many learning materials rely heavily on color perception or color coding. That is one reason that we recommend a compreshensive eye examination before a child begins school.How is color vision deficiency treated?
There is no cure for inherited color deficiency. But if the cause is an illness or eye injury, treating these conditions may improve color vision.
Using special tinted eyeglasses or wearing a red tinted contact lens on one eye can increase some people's ability to differentiate between colors, though nothing can make you truly see the deficient color.
Most color deficient persons compensate for their inability to distinguish certain colors with color cues and details that are not consciously evident to people with normal color vision. There are ways to work around the inability to see certain colors by:
- Organizing and labeling clothing, furniture or other colored objects (with the help of friends or family) for ease of recognition.
- Remembering the order of things rather than their color can also increase the chances of correctly identifying colors. For example a traffic light has red on top, yellow in the middle and green on the bottom.
Though color vision deficiency can be a frustration and may limit participation in some occupations, in most cases it is not a serious threat to vision and can be adapted to your lifestyle with time, patience and practice.
Diplopia, or double vision, is a condition where a single object is seen in duplicate.
Double and blurred vision are often thought to be the same, but they are not. In blurred vision, a single image seen by one eye appears unclear.Symptoms
- Eyes wander or appear "crossed" or misaligned
- Double vision
The symptoms described above may not necessarily mean that you have diplopia. However, if you experience one or more of these symptoms, contact your ophthalmologist for a complete exam.Causes
Diplopia may be the result of a refractive error, where light from an object is split into two images by a defect in your eye's optical system. Cataracts might, for example, cause such a defect.
Diplopia also may result from failure of both eyes to point at the object being viewed, a condition referred to as ocular misalignment. In normal vision, both eyes look at the same object. The images seen by both eyes are fused into a single picture by the brain. If your eyes do not point at the same object, the image seen by each eye is different and cannot be fused. This results in double vision.Tests and Diagnosis
A complete eye exam is necessary to determine the cause of diplopia. This includes a complete medical history, assessment of visual acuity, eye motility, and evaluation for ocular misalignment. Additional testing, such as MRI or CT scan and blood tests, may be necessary depending on the cause of diplopia.Treatment
Treatment of double vision depends on the underlying cause and may consist of eye patching, prisms, eye exercises, surgical straightening of the eye, or a combination of these options. Therapy is aimed at realigning the misaligned eye where possible without surgery and re-stimulating the part of the visual pathway to the brain that is not working correctly.